Silane coupling agents are a class of organosilicon compounds that contain two different chemical groups in the molecule, which can set up a “molecular bridge” between the interface of inorganic substance and organic substance, and connect two materials with great disparity together to improve the performance of the composite materials and increase the bonding strength. Silane coupling agents are widely used in thermosetting resin composites, thermoplastic resin composites, inorganic fillers, coatings, adhesives, sealants and other fields.
Since the fifties of the last century, thousands of varieties of silane coupling agents have been obtained, including the α-silane coupling agent which has been successfully developed by the Department of Chemistry of Nanjing University in China. Because of the unique structure, the activity of α-silane coupling agent is far greater than that of γ-silane coupling agent, which attracted great interest of scholars from various countries and, a series of studies have been conducted.
Zhou Qingli et al., Department of Chemistry of Nanjing University, published an article titled “α-functional group Silane Coupling Agent” in “Jiangsu Chemical Industry and Market Seven Daily News” in 1984. The properties and synthesis methods of α-functional silane coupling agent were analyzed in detail, the paper argued that α-functional group silane coupling agent can significantly improve the adhesion of one material to another, improve the humidity and heat resistance properties of the sealant; the most important is that when applied to silicone rubber, so that the dosage of organotin catalysts can be significantly reduced and the tack free time of sealant surface can be improved, as to the more active N, N-diethylaminomethyl triethoxysilane (ND-22), the catalyst may not used. According to the research results, the α-silane coupling agents currently used in the market are mainly ND-22, aniline methyl triethoxy silane (ND-42) etc. However, such kind of silane coupling agents are greatly limited in application because of easy discoloration and poor stability.
CN101072782 discloses a piperazine-containing α-silane coupling agent, and compared the stability of the piperazine-containing α-silane coupling agent with the α-silane coupling agent, the result displayed that piperazine-containing α-silane coupling agent has a higher stability, but such kind of silane still have the problem of high activity and easy discoloration.
EU Directive 2009/425/EC, as of Jul. 1, 2010, the EU limits the use of organic tin in all consumer products by less than 0.1%. The dosage of organotin catalysts can be reduced, when the α-silane coupling agents were applied, even may not be used. So the purpose of the present invention is to provide an α-silane coupling agent with adjustable activity and high stability, and when applied to silicone rubber, the tack free time can be significantly reduced, the curing speed and the stability of the sealant can be improved.